The proposed research will deal with the ribosome-membrane interaction in mitochondria of SACCHAROMYCES CEREVISIAE. The physiological significance of such an association will be investigated by comparing the protein synthesizing activity of the mitochondrial ribosomes, in vitro, under conditions in which the ribosomes are in association with and free from the mitochondrial membranes. To further understand the ribosome-membrane interaction, an effort will be made to eleucidate the chemical and physico-chemical nature of the ribosome-membrane association in the yeast mitochondria. This will involve the separation and analysis of the free ribosome and membrane fractions as compared to their chemical and physico-chemical properties when these are found in association with each other. Ultimately, the long term goal is to understand the interdependencies between the cytoplasmic and mitochondrial protein synthesizing systems in the synthesis and assembly of the membrane-ribosome complex during the biogenesis of mitochondria in yeast.